We investigated further the case of approval by an external body to see if this practice correlated with stability. We found that external approvals were negatively correlated with lead time, deployment frequency, and restore time, and had no correlation with change fail rate. In short, approval by an external body (such as a manager or CAB) simply doesn’t work to increase the stability of production systems, measured by the time to restore service and change fail rate. However, it certainly slows things down. It is, in fact, worse than having no change approval process at all. Our recommendation based on these results is to use a lightweight change approval process based on peer review, such as pair programming or intrateam code review, combined with a deployment pipeline to detect and reject bad changes. This process can be used for all kinds of changes, including code, infrastructure, and database changes.
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